(function () {
  class GLTFLoader extends THREE.Loader {
    constructor(manager) {
      super(manager);
      this.dracoLoader = null;
      this.ktx2Loader = null;
      this.meshoptDecoder = null;
      this.pluginCallbacks = [];
      this.register(function (parser) {
        return new GLTFMaterialsClearcoatExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFTextureBasisUExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFTextureWebPExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFMaterialsTransmissionExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFMaterialsVolumeExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFMaterialsIorExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFMaterialsSpecularExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFLightsExtension(parser);
      });
      this.register(function (parser) {
        return new GLTFMeshoptCompression(parser);
      });
    }

    load(url, onLoad, onProgress, onError) {
      const scope = this;
      let resourcePath;

      if (this.resourcePath !== '') {
        resourcePath = this.resourcePath;
      } else if (this.path !== '') {
        resourcePath = this.path;
      } else {
        resourcePath = THREE.LoaderUtils.extractUrlBase(url);
      } // Tells the LoadingManager to track an extra item, which resolves after
      // the model is fully loaded. This means the count of items loaded will
      // be incorrect, but ensures manager.onLoad() does not fire early.

      this.manager.itemStart(url);

      const _onError = function (e) {
        if (onError) {
          onError(e);
        } else {
          console.error(e);
        }

        scope.manager.itemError(url);
        scope.manager.itemEnd(url);
      };

      const loader = new THREE.FileLoader(this.manager);
      loader.setPath(this.path);
      loader.setResponseType('arraybuffer');
      loader.setRequestHeader(this.requestHeader);
      loader.setWithCredentials(this.withCredentials);
      loader.load(
        url,
        function (data) {
          try {
            scope.parse(
              data,
              resourcePath,
              function (gltf) {
                onLoad(gltf);
                scope.manager.itemEnd(url);
              },
              _onError
            );
          } catch (e) {
            _onError(e);
          }
        },
        onProgress,
        _onError
      );
    }

    setDRACOLoader(dracoLoader) {
      this.dracoLoader = dracoLoader;
      return this;
    }

    setDDSLoader() {
      throw new Error(
        'THREE.GLTFLoader: "MSFT_texture_dds" no longer supported. Please update to "KHR_texture_basisu".'
      );
    }

    setKTX2Loader(ktx2Loader) {
      this.ktx2Loader = ktx2Loader;
      return this;
    }

    setMeshoptDecoder(meshoptDecoder) {
      this.meshoptDecoder = meshoptDecoder;
      return this;
    }

    register(callback) {
      if (this.pluginCallbacks.indexOf(callback) === -1) {
        this.pluginCallbacks.push(callback);
      }

      return this;
    }

    unregister(callback) {
      if (this.pluginCallbacks.indexOf(callback) !== -1) {
        this.pluginCallbacks.splice(this.pluginCallbacks.indexOf(callback), 1);
      }

      return this;
    }

    parse(data, path, onLoad, onError) {
      let content;
      const extensions = {};
      const plugins = {};

      if (typeof data === 'string') {
        content = data;
      } else {
        const magic = THREE.LoaderUtils.decodeText(new Uint8Array(data, 0, 4));

        if (magic === BINARY_EXTENSION_HEADER_MAGIC) {
          try {
            extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(
              data
            );
          } catch (error) {
            if (onError) onError(error);
            return;
          }

          content = extensions[EXTENSIONS.KHR_BINARY_GLTF].content;
        } else {
          content = THREE.LoaderUtils.decodeText(new Uint8Array(data));
        }
      }

      const json = JSON.parse(content);

      if (json.asset === undefined || json.asset.version[0] < 2) {
        if (onError)
          onError(
            new Error(
              'THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported.'
            )
          );
        return;
      }

      const parser = new GLTFParser(json, {
        path: path || this.resourcePath || '',
        crossOrigin: this.crossOrigin,
        requestHeader: this.requestHeader,
        manager: this.manager,
        ktx2Loader: this.ktx2Loader,
        meshoptDecoder: this.meshoptDecoder,
      });
      parser.fileLoader.setRequestHeader(this.requestHeader);

      for (let i = 0; i < this.pluginCallbacks.length; i++) {
        const plugin = this.pluginCallbacks[i](parser);
        plugins[plugin.name] = plugin; // Workaround to avoid determining as unknown extension
        // in addUnknownExtensionsToUserData().
        // Remove this workaround if we move all the existing
        // extension handlers to plugin system

        extensions[plugin.name] = true;
      }

      if (json.extensionsUsed) {
        for (let i = 0; i < json.extensionsUsed.length; ++i) {
          const extensionName = json.extensionsUsed[i];
          const extensionsRequired = json.extensionsRequired || [];

          switch (extensionName) {
            case EXTENSIONS.KHR_MATERIALS_UNLIT:
              extensions[extensionName] = new GLTFMaterialsUnlitExtension();
              break;

            case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
              extensions[extensionName] =
                new GLTFMaterialsPbrSpecularGlossinessExtension();
              break;

            case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
              extensions[extensionName] = new GLTFDracoMeshCompressionExtension(
                json,
                this.dracoLoader
              );
              break;

            case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
              extensions[extensionName] = new GLTFTextureTransformExtension();
              break;

            case EXTENSIONS.KHR_MESH_QUANTIZATION:
              extensions[extensionName] = new GLTFMeshQuantizationExtension();
              break;

            default:
              if (
                extensionsRequired.indexOf(extensionName) >= 0 &&
                plugins[extensionName] === undefined
              ) {
                console.warn(
                  'THREE.GLTFLoader: Unknown extension "' + extensionName + '".'
                );
              }
          }
        }
      }

      parser.setExtensions(extensions);
      parser.setPlugins(plugins);
      parser.parse(onLoad, onError);
    }
  }
  /* GLTFREGISTRY */

  function GLTFRegistry() {
    let objects = {};
    return {
      get: function (key) {
        return objects[key];
      },
      add: function (key, object) {
        objects[key] = object;
      },
      remove: function (key) {
        delete objects[key];
      },
      removeAll: function () {
        objects = {};
      },
    };
  }
  /*********************************/

  /********** EXTENSIONS ***********/

  /*********************************/

  const EXTENSIONS = {
    KHR_BINARY_GLTF: 'KHR_binary_glTF',
    KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
    KHR_LIGHTS_PUNCTUAL: 'KHR_lights_punctual',
    KHR_MATERIALS_CLEARCOAT: 'KHR_materials_clearcoat',
    KHR_MATERIALS_IOR: 'KHR_materials_ior',
    KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
      'KHR_materials_pbrSpecularGlossiness',
    KHR_MATERIALS_SPECULAR: 'KHR_materials_specular',
    KHR_MATERIALS_TRANSMISSION: 'KHR_materials_transmission',
    KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
    KHR_MATERIALS_VOLUME: 'KHR_materials_volume',
    KHR_TEXTURE_BASISU: 'KHR_texture_basisu',
    KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
    KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
    EXT_TEXTURE_WEBP: 'EXT_texture_webp',
    EXT_MESHOPT_COMPRESSION: 'EXT_meshopt_compression',
  };
  /**
   * Punctual Lights Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
   */

  class GLTFLightsExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL; // THREE.Object3D instance caches

      this.cache = {
        refs: {},
        uses: {},
      };
    }

    _markDefs() {
      const parser = this.parser;
      const nodeDefs = this.parser.json.nodes || [];

      for (
        let nodeIndex = 0, nodeLength = nodeDefs.length;
        nodeIndex < nodeLength;
        nodeIndex++
      ) {
        const nodeDef = nodeDefs[nodeIndex];

        if (
          nodeDef.extensions &&
          nodeDef.extensions[this.name] &&
          nodeDef.extensions[this.name].light !== undefined
        ) {
          parser._addNodeRef(this.cache, nodeDef.extensions[this.name].light);
        }
      }
    }

    _loadLight(lightIndex) {
      const parser = this.parser;
      const cacheKey = 'light:' + lightIndex;
      let dependency = parser.cache.get(cacheKey);
      if (dependency) return dependency;
      const json = parser.json;
      const extensions = (json.extensions && json.extensions[this.name]) || {};
      const lightDefs = extensions.lights || [];
      const lightDef = lightDefs[lightIndex];
      let lightNode;
      const color = new THREE.Color(0xffffff);
      if (lightDef.color !== undefined) color.fromArray(lightDef.color);
      const range = lightDef.range !== undefined ? lightDef.range : 0;

      switch (lightDef.type) {
        case 'directional':
          lightNode = new THREE.DirectionalLight(color);
          lightNode.target.position.set(0, 0, -1);
          lightNode.add(lightNode.target);
          break;

        case 'point':
          lightNode = new THREE.PointLight(color);
          lightNode.distance = range;
          break;

        case 'spot':
          lightNode = new THREE.SpotLight(color);
          lightNode.distance = range; // Handle spotlight properties.

          lightDef.spot = lightDef.spot || {};
          lightDef.spot.innerConeAngle =
            lightDef.spot.innerConeAngle !== undefined
              ? lightDef.spot.innerConeAngle
              : 0;
          lightDef.spot.outerConeAngle =
            lightDef.spot.outerConeAngle !== undefined
              ? lightDef.spot.outerConeAngle
              : Math.PI / 4.0;
          lightNode.angle = lightDef.spot.outerConeAngle;
          lightNode.penumbra =
            1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
          lightNode.target.position.set(0, 0, -1);
          lightNode.add(lightNode.target);
          break;

        default:
          throw new Error(
            'THREE.GLTFLoader: Unexpected light type: ' + lightDef.type
          );
      } // Some lights (e.g. spot) default to a position other than the origin. Reset the position
      // here, because node-level parsing will only override position if explicitly specified.

      lightNode.position.set(0, 0, 0);
      lightNode.decay = 2;
      if (lightDef.intensity !== undefined)
        lightNode.intensity = lightDef.intensity;
      lightNode.name = parser.createUniqueName(
        lightDef.name || 'light_' + lightIndex
      );
      dependency = Promise.resolve(lightNode);
      parser.cache.add(cacheKey, dependency);
      return dependency;
    }

    createNodeAttachment(nodeIndex) {
      const self = this;
      const parser = this.parser;
      const json = parser.json;
      const nodeDef = json.nodes[nodeIndex];
      const lightDef =
        (nodeDef.extensions && nodeDef.extensions[this.name]) || {};
      const lightIndex = lightDef.light;
      if (lightIndex === undefined) return null;
      return this._loadLight(lightIndex).then(function (light) {
        return parser._getNodeRef(self.cache, lightIndex, light);
      });
    }
  }
  /**
   * Unlit Materials Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
   */

  class GLTFMaterialsUnlitExtension {
    constructor() {
      this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;
    }

    getMaterialType() {
      return THREE.MeshBasicMaterial;
    }

    extendParams(materialParams, materialDef, parser) {
      const pending = [];
      materialParams.color = new THREE.Color(1.0, 1.0, 1.0);
      materialParams.opacity = 1.0;
      const metallicRoughness = materialDef.pbrMetallicRoughness;

      if (metallicRoughness) {
        if (Array.isArray(metallicRoughness.baseColorFactor)) {
          const array = metallicRoughness.baseColorFactor;
          materialParams.color.fromArray(array);
          materialParams.opacity = array[3];
        }

        if (metallicRoughness.baseColorTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              'map',
              metallicRoughness.baseColorTexture
            )
          );
        }
      }

      return Promise.all(pending);
    }
  }
  /**
   * Clearcoat Materials Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
   */

  class GLTFMaterialsClearcoatExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;
    }

    getMaterialType(materialIndex) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
      return THREE.MeshPhysicalMaterial;
    }

    extendMaterialParams(materialIndex, materialParams) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];

      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }

      const pending = [];
      const extension = materialDef.extensions[this.name];

      if (extension.clearcoatFactor !== undefined) {
        materialParams.clearcoat = extension.clearcoatFactor;
      }

      if (extension.clearcoatTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'clearcoatMap',
            extension.clearcoatTexture
          )
        );
      }

      if (extension.clearcoatRoughnessFactor !== undefined) {
        materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;
      }

      if (extension.clearcoatRoughnessTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'clearcoatRoughnessMap',
            extension.clearcoatRoughnessTexture
          )
        );
      }

      if (extension.clearcoatNormalTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'clearcoatNormalMap',
            extension.clearcoatNormalTexture
          )
        );

        if (extension.clearcoatNormalTexture.scale !== undefined) {
          const scale = extension.clearcoatNormalTexture.scale; // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995

          materialParams.clearcoatNormalScale = new THREE.Vector2(
            scale,
            -scale
          );
        }
      }

      return Promise.all(pending);
    }
  }
  /**
   * Transmission Materials Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
   * Draft: https://github.com/KhronosGroup/glTF/pull/1698
   */

  class GLTFMaterialsTransmissionExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;
    }

    getMaterialType(materialIndex) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
      return THREE.MeshPhysicalMaterial;
    }

    extendMaterialParams(materialIndex, materialParams) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];

      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }

      const pending = [];
      const extension = materialDef.extensions[this.name];

      if (extension.transmissionFactor !== undefined) {
        materialParams.transmission = extension.transmissionFactor;
      }

      if (extension.transmissionTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'transmissionMap',
            extension.transmissionTexture
          )
        );
      }

      return Promise.all(pending);
    }
  }
  /**
   * Materials Volume Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
   */

  class GLTFMaterialsVolumeExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_VOLUME;
    }

    getMaterialType(materialIndex) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
      return THREE.MeshPhysicalMaterial;
    }

    extendMaterialParams(materialIndex, materialParams) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];

      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }

      const pending = [];
      const extension = materialDef.extensions[this.name];
      materialParams.thickness =
        extension.thicknessFactor !== undefined ? extension.thicknessFactor : 0;

      if (extension.thicknessTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'thicknessMap',
            extension.thicknessTexture
          )
        );
      }

      materialParams.attenuationDistance = extension.attenuationDistance || 0;
      const colorArray = extension.attenuationColor || [1, 1, 1];
      materialParams.attenuationTint = new THREE.Color(
        colorArray[0],
        colorArray[1],
        colorArray[2]
      );
      return Promise.all(pending);
    }
  }
  /**
   * Materials ior Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_ior
   */

  class GLTFMaterialsIorExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_IOR;
    }

    getMaterialType(materialIndex) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
      return THREE.MeshPhysicalMaterial;
    }

    extendMaterialParams(materialIndex, materialParams) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];

      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }

      const extension = materialDef.extensions[this.name];
      materialParams.ior = extension.ior !== undefined ? extension.ior : 1.5;
      return Promise.resolve();
    }
  }
  /**
   * Materials specular Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_specular
   */

  class GLTFMaterialsSpecularExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_MATERIALS_SPECULAR;
    }

    getMaterialType(materialIndex) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];
      if (!materialDef.extensions || !materialDef.extensions[this.name])
        return null;
      return THREE.MeshPhysicalMaterial;
    }

    extendMaterialParams(materialIndex, materialParams) {
      const parser = this.parser;
      const materialDef = parser.json.materials[materialIndex];

      if (!materialDef.extensions || !materialDef.extensions[this.name]) {
        return Promise.resolve();
      }

      const pending = [];
      const extension = materialDef.extensions[this.name];
      materialParams.specularIntensity =
        extension.specularFactor !== undefined ? extension.specularFactor : 1.0;

      if (extension.specularTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'specularIntensityMap',
            extension.specularTexture
          )
        );
      }

      const colorArray = extension.specularColorFactor || [1, 1, 1];
      materialParams.specularTint = new THREE.Color(
        colorArray[0],
        colorArray[1],
        colorArray[2]
      );

      if (extension.specularColorTexture !== undefined) {
        pending.push(
          parser
            .assignTexture(
              materialParams,
              'specularTintMap',
              extension.specularColorTexture
            )
            .then(function (texture) {
              texture.encoding = THREE.sRGBEncoding;
            })
        );
      }

      return Promise.all(pending);
    }
  }
  /**
   * BasisU THREE.Texture Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
   */

  class GLTFTextureBasisUExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.KHR_TEXTURE_BASISU;
    }

    loadTexture(textureIndex) {
      const parser = this.parser;
      const json = parser.json;
      const textureDef = json.textures[textureIndex];

      if (!textureDef.extensions || !textureDef.extensions[this.name]) {
        return null;
      }

      const extension = textureDef.extensions[this.name];
      const source = json.images[extension.source];
      const loader = parser.options.ktx2Loader;

      if (!loader) {
        if (
          json.extensionsRequired &&
          json.extensionsRequired.indexOf(this.name) >= 0
        ) {
          throw new Error(
            'THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures'
          );
        } else {
          // Assumes that the extension is optional and that a fallback texture is present
          return null;
        }
      }

      return parser.loadTextureImage(textureIndex, source, loader);
    }
  }
  /**
   * WebP THREE.Texture Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
   */

  class GLTFTextureWebPExtension {
    constructor(parser) {
      this.parser = parser;
      this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
      this.isSupported = null;
    }

    loadTexture(textureIndex) {
      const name = this.name;
      const parser = this.parser;
      const json = parser.json;
      const textureDef = json.textures[textureIndex];

      if (!textureDef.extensions || !textureDef.extensions[name]) {
        return null;
      }

      const extension = textureDef.extensions[name];
      const source = json.images[extension.source];
      let loader = parser.textureLoader;

      if (source.uri) {
        const handler = parser.options.manager.getHandler(source.uri);
        if (handler !== null) loader = handler;
      }

      return this.detectSupport().then(function (isSupported) {
        if (isSupported)
          return parser.loadTextureImage(textureIndex, source, loader);

        if (
          json.extensionsRequired &&
          json.extensionsRequired.indexOf(name) >= 0
        ) {
          throw new Error(
            'THREE.GLTFLoader: WebP required by asset but unsupported.'
          );
        } // Fall back to PNG or JPEG.

        return parser.loadTexture(textureIndex);
      });
    }

    detectSupport() {
      if (!this.isSupported) {
        this.isSupported = new Promise(function (resolve) {
          const image = new Image(); // Lossy test image. Support for lossy images doesn't guarantee support for all
          // WebP images, unfortunately.

          image.src =
            '';

          image.onload = image.onerror = function () {
            resolve(image.height === 1);
          };
        });
      }

      return this.isSupported;
    }
  }
  /**
   * meshopt BufferView Compression Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
   */

  class GLTFMeshoptCompression {
    constructor(parser) {
      this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
      this.parser = parser;
    }

    loadBufferView(index) {
      const json = this.parser.json;
      const bufferView = json.bufferViews[index];

      if (bufferView.extensions && bufferView.extensions[this.name]) {
        const extensionDef = bufferView.extensions[this.name];
        const buffer = this.parser.getDependency('buffer', extensionDef.buffer);
        const decoder = this.parser.options.meshoptDecoder;

        if (!decoder || !decoder.supported) {
          if (
            json.extensionsRequired &&
            json.extensionsRequired.indexOf(this.name) >= 0
          ) {
            throw new Error(
              'THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files'
            );
          } else {
            // Assumes that the extension is optional and that fallback buffer data is present
            return null;
          }
        }

        return Promise.all([buffer, decoder.ready]).then(function (res) {
          const byteOffset = extensionDef.byteOffset || 0;
          const byteLength = extensionDef.byteLength || 0;
          const count = extensionDef.count;
          const stride = extensionDef.byteStride;
          const result = new ArrayBuffer(count * stride);
          const source = new Uint8Array(res[0], byteOffset, byteLength);
          decoder.decodeGltfBuffer(
            new Uint8Array(result),
            count,
            stride,
            source,
            extensionDef.mode,
            extensionDef.filter
          );
          return result;
        });
      } else {
        return null;
      }
    }
  }
  /* BINARY EXTENSION */

  const BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
  const BINARY_EXTENSION_HEADER_LENGTH = 12;
  const BINARY_EXTENSION_CHUNK_TYPES = {
    JSON: 0x4e4f534a,
    BIN: 0x004e4942,
  };

  class GLTFBinaryExtension {
    constructor(data) {
      this.name = EXTENSIONS.KHR_BINARY_GLTF;
      this.content = null;
      this.body = null;
      const headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);
      this.header = {
        magic: THREE.LoaderUtils.decodeText(new Uint8Array(data.slice(0, 4))),
        version: headerView.getUint32(4, true),
        length: headerView.getUint32(8, true),
      };

      if (this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC) {
        throw new Error('THREE.GLTFLoader: Unsupported glTF-Binary header.');
      } else if (this.header.version < 2.0) {
        throw new Error('THREE.GLTFLoader: Legacy binary file detected.');
      }

      const chunkContentsLength =
        this.header.length - BINARY_EXTENSION_HEADER_LENGTH;
      const chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
      let chunkIndex = 0;

      while (chunkIndex < chunkContentsLength) {
        const chunkLength = chunkView.getUint32(chunkIndex, true);
        chunkIndex += 4;
        const chunkType = chunkView.getUint32(chunkIndex, true);
        chunkIndex += 4;

        if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {
          const contentArray = new Uint8Array(
            data,
            BINARY_EXTENSION_HEADER_LENGTH + chunkIndex,
            chunkLength
          );
          this.content = THREE.LoaderUtils.decodeText(contentArray);
        } else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {
          const byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
          this.body = data.slice(byteOffset, byteOffset + chunkLength);
        } // Clients must ignore chunks with unknown types.

        chunkIndex += chunkLength;
      }

      if (this.content === null) {
        throw new Error('THREE.GLTFLoader: JSON content not found.');
      }
    }
  }
  /**
   * DRACO THREE.Mesh Compression Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
   */

  class GLTFDracoMeshCompressionExtension {
    constructor(json, dracoLoader) {
      if (!dracoLoader) {
        throw new Error('THREE.GLTFLoader: No DRACOLoader instance provided.');
      }

      this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
      this.json = json;
      this.dracoLoader = dracoLoader;
      this.dracoLoader.preload();
    }

    decodePrimitive(primitive, parser) {
      const json = this.json;
      const dracoLoader = this.dracoLoader;
      const bufferViewIndex = primitive.extensions[this.name].bufferView;
      const gltfAttributeMap = primitive.extensions[this.name].attributes;
      const threeAttributeMap = {};
      const attributeNormalizedMap = {};
      const attributeTypeMap = {};

      for (const attributeName in gltfAttributeMap) {
        const threeAttributeName =
          ATTRIBUTES[attributeName] || attributeName.toLowerCase();
        threeAttributeMap[threeAttributeName] = gltfAttributeMap[attributeName];
      }

      for (const attributeName in primitive.attributes) {
        const threeAttributeName =
          ATTRIBUTES[attributeName] || attributeName.toLowerCase();

        if (gltfAttributeMap[attributeName] !== undefined) {
          const accessorDef =
            json.accessors[primitive.attributes[attributeName]];
          const componentType =
            WEBGL_COMPONENT_TYPES[accessorDef.componentType];
          attributeTypeMap[threeAttributeName] = componentType;
          attributeNormalizedMap[threeAttributeName] =
            accessorDef.normalized === true;
        }
      }

      return parser
        .getDependency('bufferView', bufferViewIndex)
        .then(function (bufferView) {
          return new Promise(function (resolve) {
            dracoLoader.decodeDracoFile(
              bufferView,
              function (geometry) {
                for (const attributeName in geometry.attributes) {
                  const attribute = geometry.attributes[attributeName];
                  const normalized = attributeNormalizedMap[attributeName];
                  if (normalized !== undefined)
                    attribute.normalized = normalized;
                }

                resolve(geometry);
              },
              threeAttributeMap,
              attributeTypeMap
            );
          });
        });
    }
  }
  /**
   * THREE.Texture Transform Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
   */

  class GLTFTextureTransformExtension {
    constructor() {
      this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;
    }

    extendTexture(texture, transform) {
      if (transform.texCoord !== undefined) {
        console.warn(
          'THREE.GLTFLoader: Custom UV sets in "' +
            this.name +
            '" extension not yet supported.'
        );
      }

      if (
        transform.offset === undefined &&
        transform.rotation === undefined &&
        transform.scale === undefined
      ) {
        // See https://github.com/mrdoob/three.js/issues/21819.
        return texture;
      }

      texture = texture.clone();

      if (transform.offset !== undefined) {
        texture.offset.fromArray(transform.offset);
      }

      if (transform.rotation !== undefined) {
        texture.rotation = transform.rotation;
      }

      if (transform.scale !== undefined) {
        texture.repeat.fromArray(transform.scale);
      }

      texture.needsUpdate = true;
      return texture;
    }
  }
  /**
   * Specular-Glossiness Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
   */

  /**
   * A sub class of StandardMaterial with some of the functionality
   * changed via the `onBeforeCompile` callback
   * @pailhead
   */

  class GLTFMeshStandardSGMaterial extends THREE.MeshStandardMaterial {
    constructor(params) {
      super();
      this.isGLTFSpecularGlossinessMaterial = true; //various chunks that need replacing

      const specularMapParsFragmentChunk = [
        '#ifdef USE_SPECULARMAP',
        '	uniform sampler2D specularMap;',
        '#endif',
      ].join('\n');
      const glossinessMapParsFragmentChunk = [
        '#ifdef USE_GLOSSINESSMAP',
        '	uniform sampler2D glossinessMap;',
        '#endif',
      ].join('\n');
      const specularMapFragmentChunk = [
        'vec3 specularFactor = specular;',
        '#ifdef USE_SPECULARMAP',
        '	vec4 texelSpecular = texture2D( specularMap, vUv );',
        '	texelSpecular = sRGBToLinear( texelSpecular );',
        '	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
        '	specularFactor *= texelSpecular.rgb;',
        '#endif',
      ].join('\n');
      const glossinessMapFragmentChunk = [
        'float glossinessFactor = glossiness;',
        '#ifdef USE_GLOSSINESSMAP',
        '	vec4 texelGlossiness = texture2D( glossinessMap, vUv );',
        '	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture',
        '	glossinessFactor *= texelGlossiness.a;',
        '#endif',
      ].join('\n');
      const lightPhysicalFragmentChunk = [
        'PhysicalMaterial material;',
        'material.diffuseColor = diffuseColor.rgb * ( 1. - max( specularFactor.r, max( specularFactor.g, specularFactor.b ) ) );',
        'vec3 dxy = max( abs( dFdx( geometryNormal ) ), abs( dFdy( geometryNormal ) ) );',
        'float geometryRoughness = max( max( dxy.x, dxy.y ), dxy.z );',
        'material.roughness = max( 1.0 - glossinessFactor, 0.0525 ); // 0.0525 corresponds to the base mip of a 256 cubemap.',
        'material.roughness += geometryRoughness;',
        'material.roughness = min( material.roughness, 1.0 );',
        'material.specularColor = specularFactor;',
      ].join('\n');
      const uniforms = {
        specular: {
          value: new THREE.Color().setHex(0xffffff),
        },
        glossiness: {
          value: 1,
        },
        specularMap: {
          value: null,
        },
        glossinessMap: {
          value: null,
        },
      };
      this._extraUniforms = uniforms;

      this.onBeforeCompile = function (shader) {
        for (const uniformName in uniforms) {
          shader.uniforms[uniformName] = uniforms[uniformName];
        }

        shader.fragmentShader = shader.fragmentShader
          .replace('uniform float roughness;', 'uniform vec3 specular;')
          .replace('uniform float metalness;', 'uniform float glossiness;')
          .replace(
            '#include <roughnessmap_pars_fragment>',
            specularMapParsFragmentChunk
          )
          .replace(
            '#include <metalnessmap_pars_fragment>',
            glossinessMapParsFragmentChunk
          )
          .replace('#include <roughnessmap_fragment>', specularMapFragmentChunk)
          .replace(
            '#include <metalnessmap_fragment>',
            glossinessMapFragmentChunk
          )
          .replace(
            '#include <lights_physical_fragment>',
            lightPhysicalFragmentChunk
          );
      };

      Object.defineProperties(this, {
        specular: {
          get: function () {
            return uniforms.specular.value;
          },
          set: function (v) {
            uniforms.specular.value = v;
          },
        },
        specularMap: {
          get: function () {
            return uniforms.specularMap.value;
          },
          set: function (v) {
            uniforms.specularMap.value = v;

            if (v) {
              this.defines.USE_SPECULARMAP = ''; // USE_UV is set by the renderer for specular maps
            } else {
              delete this.defines.USE_SPECULARMAP;
            }
          },
        },
        glossiness: {
          get: function () {
            return uniforms.glossiness.value;
          },
          set: function (v) {
            uniforms.glossiness.value = v;
          },
        },
        glossinessMap: {
          get: function () {
            return uniforms.glossinessMap.value;
          },
          set: function (v) {
            uniforms.glossinessMap.value = v;

            if (v) {
              this.defines.USE_GLOSSINESSMAP = '';
              this.defines.USE_UV = '';
            } else {
              delete this.defines.USE_GLOSSINESSMAP;
              delete this.defines.USE_UV;
            }
          },
        },
      });
      delete this.metalness;
      delete this.roughness;
      delete this.metalnessMap;
      delete this.roughnessMap;
      this.setValues(params);
    }

    copy(source) {
      super.copy(source);
      this.specularMap = source.specularMap;
      this.specular.copy(source.specular);
      this.glossinessMap = source.glossinessMap;
      this.glossiness = source.glossiness;
      delete this.metalness;
      delete this.roughness;
      delete this.metalnessMap;
      delete this.roughnessMap;
      return this;
    }
  }

  class GLTFMaterialsPbrSpecularGlossinessExtension {
    constructor() {
      this.name = EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS;
      this.specularGlossinessParams = [
        'color',
        'map',
        'lightMap',
        'lightMapIntensity',
        'aoMap',
        'aoMapIntensity',
        'emissive',
        'emissiveIntensity',
        'emissiveMap',
        'bumpMap',
        'bumpScale',
        'normalMap',
        'normalMapType',
        'displacementMap',
        'displacementScale',
        'displacementBias',
        'specularMap',
        'specular',
        'glossinessMap',
        'glossiness',
        'alphaMap',
        'envMap',
        'envMapIntensity',
        'refractionRatio',
      ];
    }

    getMaterialType() {
      return GLTFMeshStandardSGMaterial;
    }

    extendParams(materialParams, materialDef, parser) {
      const pbrSpecularGlossiness = materialDef.extensions[this.name];
      materialParams.color = new THREE.Color(1.0, 1.0, 1.0);
      materialParams.opacity = 1.0;
      const pending = [];

      if (Array.isArray(pbrSpecularGlossiness.diffuseFactor)) {
        const array = pbrSpecularGlossiness.diffuseFactor;
        materialParams.color.fromArray(array);
        materialParams.opacity = array[3];
      }

      if (pbrSpecularGlossiness.diffuseTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'map',
            pbrSpecularGlossiness.diffuseTexture
          )
        );
      }

      materialParams.emissive = new THREE.Color(0.0, 0.0, 0.0);
      materialParams.glossiness =
        pbrSpecularGlossiness.glossinessFactor !== undefined
          ? pbrSpecularGlossiness.glossinessFactor
          : 1.0;
      materialParams.specular = new THREE.Color(1.0, 1.0, 1.0);

      if (Array.isArray(pbrSpecularGlossiness.specularFactor)) {
        materialParams.specular.fromArray(pbrSpecularGlossiness.specularFactor);
      }

      if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {
        const specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
        pending.push(
          parser.assignTexture(materialParams, 'glossinessMap', specGlossMapDef)
        );
        pending.push(
          parser.assignTexture(materialParams, 'specularMap', specGlossMapDef)
        );
      }

      return Promise.all(pending);
    }

    createMaterial(materialParams) {
      const material = new GLTFMeshStandardSGMaterial(materialParams);
      material.fog = true;
      material.color = materialParams.color;
      material.map =
        materialParams.map === undefined ? null : materialParams.map;
      material.lightMap = null;
      material.lightMapIntensity = 1.0;
      material.aoMap =
        materialParams.aoMap === undefined ? null : materialParams.aoMap;
      material.aoMapIntensity = 1.0;
      material.emissive = materialParams.emissive;
      material.emissiveIntensity = 1.0;
      material.emissiveMap =
        materialParams.emissiveMap === undefined
          ? null
          : materialParams.emissiveMap;
      material.bumpMap =
        materialParams.bumpMap === undefined ? null : materialParams.bumpMap;
      material.bumpScale = 1;
      material.normalMap =
        materialParams.normalMap === undefined
          ? null
          : materialParams.normalMap;
      material.normalMapType = THREE.TangentSpaceNormalMap;
      if (materialParams.normalScale)
        material.normalScale = materialParams.normalScale;
      material.displacementMap = null;
      material.displacementScale = 1;
      material.displacementBias = 0;
      material.specularMap =
        materialParams.specularMap === undefined
          ? null
          : materialParams.specularMap;
      material.specular = materialParams.specular;
      material.glossinessMap =
        materialParams.glossinessMap === undefined
          ? null
          : materialParams.glossinessMap;
      material.glossiness = materialParams.glossiness;
      material.alphaMap = null;
      material.envMap =
        materialParams.envMap === undefined ? null : materialParams.envMap;
      material.envMapIntensity = 1.0;
      material.refractionRatio = 0.98;
      return material;
    }
  }
  /**
   * THREE.Mesh Quantization Extension
   *
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
   */

  class GLTFMeshQuantizationExtension {
    constructor() {
      this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;
    }
  }
  /*********************************/

  /********** INTERPOLATION ********/

  /*********************************/
  // Spline Interpolation
  // Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation

  class GLTFCubicSplineInterpolant extends THREE.Interpolant {
    constructor(parameterPositions, sampleValues, sampleSize, resultBuffer) {
      super(parameterPositions, sampleValues, sampleSize, resultBuffer);
    }

    copySampleValue_(index) {
      // Copies a sample value to the result buffer. See description of glTF
      // CUBICSPLINE values layout in interpolate_() function below.
      const result = this.resultBuffer,
        values = this.sampleValues,
        valueSize = this.valueSize,
        offset = index * valueSize * 3 + valueSize;

      for (let i = 0; i !== valueSize; i++) {
        result[i] = values[offset + i];
      }

      return result;
    }
  }

  GLTFCubicSplineInterpolant.prototype.beforeStart_ =
    GLTFCubicSplineInterpolant.prototype.copySampleValue_;
  GLTFCubicSplineInterpolant.prototype.afterEnd_ =
    GLTFCubicSplineInterpolant.prototype.copySampleValue_;

  GLTFCubicSplineInterpolant.prototype.interpolate_ = function (i1, t0, t, t1) {
    const result = this.resultBuffer;
    const values = this.sampleValues;
    const stride = this.valueSize;
    const stride2 = stride * 2;
    const stride3 = stride * 3;
    const td = t1 - t0;
    const p = (t - t0) / td;
    const pp = p * p;
    const ppp = pp * p;
    const offset1 = i1 * stride3;
    const offset0 = offset1 - stride3;
    const s2 = -2 * ppp + 3 * pp;
    const s3 = ppp - pp;
    const s0 = 1 - s2;
    const s1 = s3 - pp + p; // Layout of keyframe output values for CUBICSPLINE animations:
    //   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]

    for (let i = 0; i !== stride; i++) {
      const p0 = values[offset0 + i + stride]; // splineVertex_k

      const m0 = values[offset0 + i + stride2] * td; // outTangent_k * (t_k+1 - t_k)

      const p1 = values[offset1 + i + stride]; // splineVertex_k+1

      const m1 = values[offset1 + i] * td; // inTangent_k+1 * (t_k+1 - t_k)

      result[i] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;
    }

    return result;
  };

  const _q = new THREE.Quaternion();

  class GLTFCubicSplineQuaternionInterpolant extends GLTFCubicSplineInterpolant {
    interpolate_(i1, t0, t, t1) {
      const result = super.interpolate_(i1, t0, t, t1);

      _q.fromArray(result).normalize().toArray(result);

      return result;
    }
  }
  /*********************************/

  /********** INTERNALS ************/

  /*********************************/

  /* CONSTANTS */

  const WEBGL_CONSTANTS = {
    FLOAT: 5126,
    //FLOAT_MAT2: 35674,
    FLOAT_MAT3: 35675,
    FLOAT_MAT4: 35676,
    FLOAT_VEC2: 35664,
    FLOAT_VEC3: 35665,
    FLOAT_VEC4: 35666,
    LINEAR: 9729,
    REPEAT: 10497,
    SAMPLER_2D: 35678,
    POINTS: 0,
    LINES: 1,
    LINE_LOOP: 2,
    LINE_STRIP: 3,
    TRIANGLES: 4,
    TRIANGLE_STRIP: 5,
    TRIANGLE_FAN: 6,
    UNSIGNED_BYTE: 5121,
    UNSIGNED_SHORT: 5123,
  };
  const WEBGL_COMPONENT_TYPES = {
    5120: Int8Array,
    5121: Uint8Array,
    5122: Int16Array,
    5123: Uint16Array,
    5125: Uint32Array,
    5126: Float32Array,
  };
  const WEBGL_FILTERS = {
    9728: THREE.NearestFilter,
    9729: THREE.LinearFilter,
    9984: THREE.NearestMipmapNearestFilter,
    9985: THREE.LinearMipmapNearestFilter,
    9986: THREE.NearestMipmapLinearFilter,
    9987: THREE.LinearMipmapLinearFilter,
  };
  const WEBGL_WRAPPINGS = {
    33071: THREE.ClampToEdgeWrapping,
    33648: THREE.MirroredRepeatWrapping,
    10497: THREE.RepeatWrapping,
  };
  const WEBGL_TYPE_SIZES = {
    SCALAR: 1,
    VEC2: 2,
    VEC3: 3,
    VEC4: 4,
    MAT2: 4,
    MAT3: 9,
    MAT4: 16,
  };
  const ATTRIBUTES = {
    POSITION: 'position',
    NORMAL: 'normal',
    TANGENT: 'tangent',
    TEXCOORD_0: 'uv',
    TEXCOORD_1: 'uv2',
    COLOR_0: 'color',
    WEIGHTS_0: 'skinWeight',
    JOINTS_0: 'skinIndex',
  };
  const PATH_PROPERTIES = {
    scale: 'scale',
    translation: 'position',
    rotation: 'quaternion',
    weights: 'morphTargetInfluences',
  };
  const INTERPOLATION = {
    CUBICSPLINE: undefined,
    // We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
    // keyframe track will be initialized with a default interpolation type, then modified.
    LINEAR: THREE.InterpolateLinear,
    STEP: THREE.InterpolateDiscrete,
  };
  const ALPHA_MODES = {
    OPAQUE: 'OPAQUE',
    MASK: 'MASK',
    BLEND: 'BLEND',
  };
  /* UTILITY FUNCTIONS */

  function resolveURL(url, path) {
    // Invalid URL
    if (typeof url !== 'string' || url === '') return ''; // Host Relative URL

    if (/^https?:\/\//i.test(path) && /^\//.test(url)) {
      path = path.replace(/(^https?:\/\/[^\/]+).*/i, '$1');
    } // Absolute URL http://,https://,//

    if (/^(https?:)?\/\//i.test(url)) return url; // Data URI

    if (/^data:.*,.*$/i.test(url)) return url; // Blob URL

    if (/^blob:.*$/i.test(url)) return url; // Relative URL

    return path + url;
  }
  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
   */

  function createDefaultMaterial(cache) {
    if (cache['DefaultMaterial'] === undefined) {
      cache['DefaultMaterial'] = new THREE.MeshStandardMaterial({
        color: 0xffffff,
        emissive: 0x000000,
        metalness: 1,
        roughness: 1,
        transparent: false,
        depthTest: true,
        side: THREE.FrontSide,
      });
    }

    return cache['DefaultMaterial'];
  }

  function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {
    // Add unknown glTF extensions to an object's userData.
    for (const name in objectDef.extensions) {
      if (knownExtensions[name] === undefined) {
        object.userData.gltfExtensions = object.userData.gltfExtensions || {};
        object.userData.gltfExtensions[name] = objectDef.extensions[name];
      }
    }
  }
  /**
   * @param {Object3D|Material|BufferGeometry} object
   * @param {GLTF.definition} gltfDef
   */

  function assignExtrasToUserData(object, gltfDef) {
    if (gltfDef.extras !== undefined) {
      if (typeof gltfDef.extras === 'object') {
        Object.assign(object.userData, gltfDef.extras);
      } else {
        console.warn(
          'THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras
        );
      }
    }
  }
  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
   *
   * @param {BufferGeometry} geometry
   * @param {Array<GLTF.Target>} targets
   * @param {GLTFParser} parser
   * @return {Promise<BufferGeometry>}
   */

  function addMorphTargets(geometry, targets, parser) {
    let hasMorphPosition = false;
    let hasMorphNormal = false;

    for (let i = 0, il = targets.length; i < il; i++) {
      const target = targets[i];
      if (target.POSITION !== undefined) hasMorphPosition = true;
      if (target.NORMAL !== undefined) hasMorphNormal = true;
      if (hasMorphPosition && hasMorphNormal) break;
    }

    if (!hasMorphPosition && !hasMorphNormal) return Promise.resolve(geometry);
    const pendingPositionAccessors = [];
    const pendingNormalAccessors = [];

    for (let i = 0, il = targets.length; i < il; i++) {
      const target = targets[i];

      if (hasMorphPosition) {
        const pendingAccessor =
          target.POSITION !== undefined
            ? parser.getDependency('accessor', target.POSITION)
            : geometry.attributes.position;
        pendingPositionAccessors.push(pendingAccessor);
      }

      if (hasMorphNormal) {
        const pendingAccessor =
          target.NORMAL !== undefined
            ? parser.getDependency('accessor', target.NORMAL)
            : geometry.attributes.normal;
        pendingNormalAccessors.push(pendingAccessor);
      }
    }

    return Promise.all([
      Promise.all(pendingPositionAccessors),
      Promise.all(pendingNormalAccessors),
    ]).then(function (accessors) {
      const morphPositions = accessors[0];
      const morphNormals = accessors[1];
      if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
      if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;
      geometry.morphTargetsRelative = true;
      return geometry;
    });
  }
  /**
   * @param {Mesh} mesh
   * @param {GLTF.Mesh} meshDef
   */

  function updateMorphTargets(mesh, meshDef) {
    mesh.updateMorphTargets();

    if (meshDef.weights !== undefined) {
      for (let i = 0, il = meshDef.weights.length; i < il; i++) {
        mesh.morphTargetInfluences[i] = meshDef.weights[i];
      }
    } // .extras has user-defined data, so check that .extras.targetNames is an array.

    if (meshDef.extras && Array.isArray(meshDef.extras.targetNames)) {
      const targetNames = meshDef.extras.targetNames;

      if (mesh.morphTargetInfluences.length === targetNames.length) {
        mesh.morphTargetDictionary = {};

        for (let i = 0, il = targetNames.length; i < il; i++) {
          mesh.morphTargetDictionary[targetNames[i]] = i;
        }
      } else {
        console.warn(
          'THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.'
        );
      }
    }
  }

  function createPrimitiveKey(primitiveDef) {
    const dracoExtension =
      primitiveDef.extensions &&
      primitiveDef.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION];
    let geometryKey;

    if (dracoExtension) {
      geometryKey =
        'draco:' +
        dracoExtension.bufferView +
        ':' +
        dracoExtension.indices +
        ':' +
        createAttributesKey(dracoExtension.attributes);
    } else {
      geometryKey =
        primitiveDef.indices +
        ':' +
        createAttributesKey(primitiveDef.attributes) +
        ':' +
        primitiveDef.mode;
    }

    return geometryKey;
  }

  function createAttributesKey(attributes) {
    let attributesKey = '';
    const keys = Object.keys(attributes).sort();

    for (let i = 0, il = keys.length; i < il; i++) {
      attributesKey += keys[i] + ':' + attributes[keys[i]] + ';';
    }

    return attributesKey;
  }

  function getNormalizedComponentScale(constructor) {
    // Reference:
    // https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization#encoding-quantized-data
    switch (constructor) {
      case Int8Array:
        return 1 / 127;

      case Uint8Array:
        return 1 / 255;

      case Int16Array:
        return 1 / 32767;

      case Uint16Array:
        return 1 / 65535;

      default:
        throw new Error(
          'THREE.GLTFLoader: Unsupported normalized accessor component type.'
        );
    }
  }
  /* GLTF PARSER */

  class GLTFParser {
    constructor(json = {}, options = {}) {
      this.json = json;
      this.extensions = {};
      this.plugins = {};
      this.options = options; // loader object cache

      this.cache = new GLTFRegistry(); // associations between Three.js objects and glTF elements

      this.associations = new Map(); // THREE.BufferGeometry caching

      this.primitiveCache = {}; // THREE.Object3D instance caches

      this.meshCache = {
        refs: {},
        uses: {},
      };
      this.cameraCache = {
        refs: {},
        uses: {},
      };
      this.lightCache = {
        refs: {},
        uses: {},
      };
      this.textureCache = {}; // Track node names, to ensure no duplicates

      this.nodeNamesUsed = {}; // Use an THREE.ImageBitmapLoader if imageBitmaps are supported. Moves much of the
      // expensive work of uploading a texture to the GPU off the main thread.

      if (
        typeof createImageBitmap !== 'undefined' &&
        /Firefox/.test(navigator.userAgent) === false
      ) {
        this.textureLoader = new THREE.ImageBitmapLoader(this.options.manager);
      } else {
        this.textureLoader = new THREE.TextureLoader(this.options.manager);
      }

      this.textureLoader.setCrossOrigin(this.options.crossOrigin);
      this.textureLoader.setRequestHeader(this.options.requestHeader);
      this.fileLoader = new THREE.FileLoader(this.options.manager);
      this.fileLoader.setResponseType('arraybuffer');

      if (this.options.crossOrigin === 'use-credentials') {
        this.fileLoader.setWithCredentials(true);
      }
    }

    setExtensions(extensions) {
      this.extensions = extensions;
    }

    setPlugins(plugins) {
      this.plugins = plugins;
    }

    parse(onLoad, onError) {
      const parser = this;
      const json = this.json;
      const extensions = this.extensions; // Clear the loader cache

      this.cache.removeAll(); // Mark the special nodes/meshes in json for efficient parse

      this._invokeAll(function (ext) {
        return ext._markDefs && ext._markDefs();
      });

      Promise.all(
        this._invokeAll(function (ext) {
          return ext.beforeRoot && ext.beforeRoot();
        })
      )
        .then(function () {
          return Promise.all([
            parser.getDependencies('scene'),
            parser.getDependencies('animation'),
            parser.getDependencies('camera'),
          ]);
        })
        .then(function (dependencies) {
          const result = {
            scene: dependencies[0][json.scene || 0],
            scenes: dependencies[0],
            animations: dependencies[1],
            cameras: dependencies[2],
            asset: json.asset,
            parser: parser,
            userData: {},
          };
          addUnknownExtensionsToUserData(extensions, result, json);
          assignExtrasToUserData(result, json);
          Promise.all(
            parser._invokeAll(function (ext) {
              return ext.afterRoot && ext.afterRoot(result);
            })
          ).then(function () {
            onLoad(result);
          });
        })
        .catch(onError);
    }
    /**
     * Marks the special nodes/meshes in json for efficient parse.
     */

    _markDefs() {
      const nodeDefs = this.json.nodes || [];
      const skinDefs = this.json.skins || [];
      const meshDefs = this.json.meshes || []; // Nothing in the node definition indicates whether it is a THREE.Bone or an
      // THREE.Object3D. Use the skins' joint references to mark bones.

      for (
        let skinIndex = 0, skinLength = skinDefs.length;
        skinIndex < skinLength;
        skinIndex++
      ) {
        const joints = skinDefs[skinIndex].joints;

        for (let i = 0, il = joints.length; i < il; i++) {
          nodeDefs[joints[i]].isBone = true;
        }
      } // Iterate over all nodes, marking references to shared resources,
      // as well as skeleton joints.

      for (
        let nodeIndex = 0, nodeLength = nodeDefs.length;
        nodeIndex < nodeLength;
        nodeIndex++
      ) {
        const nodeDef = nodeDefs[nodeIndex];

        if (nodeDef.mesh !== undefined) {
          this._addNodeRef(this.meshCache, nodeDef.mesh); // Nothing in the mesh definition indicates whether it is
          // a THREE.SkinnedMesh or THREE.Mesh. Use the node's mesh reference
          // to mark THREE.SkinnedMesh if node has skin.

          if (nodeDef.skin !== undefined) {
            meshDefs[nodeDef.mesh].isSkinnedMesh = true;
          }
        }

        if (nodeDef.camera !== undefined) {
          this._addNodeRef(this.cameraCache, nodeDef.camera);
        }
      }
    }
    /**
     * Counts references to shared node / THREE.Object3D resources. These resources
     * can be reused, or "instantiated", at multiple nodes in the scene
     * hierarchy. THREE.Mesh, Camera, and Light instances are instantiated and must
     * be marked. Non-scenegraph resources (like Materials, Geometries, and
     * Textures) can be reused directly and are not marked here.
     *
     * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
     */

    _addNodeRef(cache, index) {
      if (index === undefined) return;

      if (cache.refs[index] === undefined) {
        cache.refs[index] = cache.uses[index] = 0;
      }

      cache.refs[index]++;
    }
    /** Returns a reference to a shared resource, cloning it if necessary. */

    _getNodeRef(cache, index, object) {
      if (cache.refs[index] <= 1) return object;
      const ref = object.clone();
      ref.name += '_instance_' + cache.uses[index]++;
      return ref;
    }

    _invokeOne(func) {
      const extensions = Object.values(this.plugins);
      extensions.push(this);

      for (let i = 0; i < extensions.length; i++) {
        const result = func(extensions[i]);
        if (result) return result;
      }

      return null;
    }

    _invokeAll(func) {
      const extensions = Object.values(this.plugins);
      extensions.unshift(this);
      const pending = [];

      for (let i = 0; i < extensions.length; i++) {
        const result = func(extensions[i]);
        if (result) pending.push(result);
      }

      return pending;
    }
    /**
     * Requests the specified dependency asynchronously, with caching.
     * @param {string} type
     * @param {number} index
     * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
     */

    getDependency(type, index) {
      const cacheKey = type + ':' + index;
      let dependency = this.cache.get(cacheKey);

      if (!dependency) {
        switch (type) {
          case 'scene':
            dependency = this.loadScene(index);
            break;

          case 'node':
            dependency = this.loadNode(index);
            break;

          case 'mesh':
            dependency = this._invokeOne(function (ext) {
              return ext.loadMesh && ext.loadMesh(index);
            });
            break;

          case 'accessor':
            dependency = this.loadAccessor(index);
            break;

          case 'bufferView':
            dependency = this._invokeOne(function (ext) {
              return ext.loadBufferView && ext.loadBufferView(index);
            });
            break;

          case 'buffer':
            dependency = this.loadBuffer(index);
            break;

          case 'material':
            dependency = this._invokeOne(function (ext) {
              return ext.loadMaterial && ext.loadMaterial(index);
            });
            break;

          case 'texture':
            dependency = this._invokeOne(function (ext) {
              return ext.loadTexture && ext.loadTexture(index);
            });
            break;

          case 'skin':
            dependency = this.loadSkin(index);
            break;

          case 'animation':
            dependency = this.loadAnimation(index);
            break;

          case 'camera':
            dependency = this.loadCamera(index);
            break;

          default:
            throw new Error('Unknown type: ' + type);
        }

        this.cache.add(cacheKey, dependency);
      }

      return dependency;
    }
    /**
     * Requests all dependencies of the specified type asynchronously, with caching.
     * @param {string} type
     * @return {Promise<Array<Object>>}
     */

    getDependencies(type) {
      let dependencies = this.cache.get(type);

      if (!dependencies) {
        const parser = this;
        const defs = this.json[type + (type === 'mesh' ? 'es' : 's')] || [];
        dependencies = Promise.all(
          defs.map(function (def, index) {
            return parser.getDependency(type, index);
          })
        );
        this.cache.add(type, dependencies);
      }

      return dependencies;
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
     * @param {number} bufferIndex
     * @return {Promise<ArrayBuffer>}
     */

    loadBuffer(bufferIndex) {
      const bufferDef = this.json.buffers[bufferIndex];
      const loader = this.fileLoader;

      if (bufferDef.type && bufferDef.type !== 'arraybuffer') {
        throw new Error(
          'THREE.GLTFLoader: ' +
            bufferDef.type +
            ' buffer type is not supported.'
        );
      } // If present, GLB container is required to be the first buffer.

      if (bufferDef.uri === undefined && bufferIndex === 0) {
        return Promise.resolve(
          this.extensions[EXTENSIONS.KHR_BINARY_GLTF].body
        );
      }

      const options = this.options;
      return new Promise(function (resolve, reject) {
        loader.load(
          resolveURL(bufferDef.uri, options.path),
          resolve,
          undefined,
          function () {
            reject(
              new Error(
                'THREE.GLTFLoader: Failed to load buffer "' +
                  bufferDef.uri +
                  '".'
              )
            );
          }
        );
      });
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
     * @param {number} bufferViewIndex
     * @return {Promise<ArrayBuffer>}
     */

    loadBufferView(bufferViewIndex) {
      const bufferViewDef = this.json.bufferViews[bufferViewIndex];
      return this.getDependency('buffer', bufferViewDef.buffer).then(function (
        buffer
      ) {
        const byteLength = bufferViewDef.byteLength || 0;
        const byteOffset = bufferViewDef.byteOffset || 0;
        return buffer.slice(byteOffset, byteOffset + byteLength);
      });
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
     * @param {number} accessorIndex
     * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
     */

    loadAccessor(accessorIndex) {
      const parser = this;
      const json = this.json;
      const accessorDef = this.json.accessors[accessorIndex];

      if (
        accessorDef.bufferView === undefined &&
        accessorDef.sparse === undefined
      ) {
        // Ignore empty accessors, which may be used to declare runtime
        // information about attributes coming from another source (e.g. Draco
        // compression extension).
        return Promise.resolve(null);
      }

      const pendingBufferViews = [];

      if (accessorDef.bufferView !== undefined) {
        pendingBufferViews.push(
          this.getDependency('bufferView', accessorDef.bufferView)
        );
      } else {
        pendingBufferViews.push(null);
      }

      if (accessorDef.sparse !== undefined) {
        pendingBufferViews.push(
          this.getDependency(
            'bufferView',
            accessorDef.sparse.indices.bufferView
          )
        );
        pendingBufferViews.push(
          this.getDependency('bufferView', accessorDef.sparse.values.bufferView)
        );
      }

      return Promise.all(pendingBufferViews).then(function (bufferViews) {
        const bufferView = bufferViews[0];
        const itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
        const TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType]; // For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.

        const elementBytes = TypedArray.BYTES_PER_ELEMENT;
        const itemBytes = elementBytes * itemSize;
        const byteOffset = accessorDef.byteOffset || 0;
        const byteStride =
          accessorDef.bufferView !== undefined
            ? json.bufferViews[accessorDef.bufferView].byteStride
            : undefined;
        const normalized = accessorDef.normalized === true;
        let array, bufferAttribute; // The buffer is not interleaved if the stride is the item size in bytes.

        if (byteStride && byteStride !== itemBytes) {
          // Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own THREE.InterleavedBuffer
          // This makes sure that IBA.count reflects accessor.count properly
          const ibSlice = Math.floor(byteOffset / byteStride);
          const ibCacheKey =
            'InterleavedBuffer:' +
            accessorDef.bufferView +
            ':' +
            accessorDef.componentType +
            ':' +
            ibSlice +
            ':' +
            accessorDef.count;
          let ib = parser.cache.get(ibCacheKey);

          if (!ib) {
            array = new TypedArray(
              bufferView,
              ibSlice * byteStride,
              (accessorDef.count * byteStride) / elementBytes
            ); // Integer parameters to IB/IBA are in array elements, not bytes.

            ib = new THREE.InterleavedBuffer(array, byteStride / elementBytes);
            parser.cache.add(ibCacheKey, ib);
          }

          bufferAttribute = new THREE.InterleavedBufferAttribute(
            ib,
            itemSize,
            (byteOffset % byteStride) / elementBytes,
            normalized
          );
        } else {
          if (bufferView === null) {
            array = new TypedArray(accessorDef.count * itemSize);
          } else {
            array = new TypedArray(
              bufferView,
              byteOffset,
              accessorDef.count * itemSize
            );
          }

          bufferAttribute = new THREE.BufferAttribute(
            array,
            itemSize,
            normalized
          );
        } // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors

        if (accessorDef.sparse !== undefined) {
          const itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
          const TypedArrayIndices =
            WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType];
          const byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
          const byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;
          const sparseIndices = new TypedArrayIndices(
            bufferViews[1],
            byteOffsetIndices,
            accessorDef.sparse.count * itemSizeIndices
          );
          const sparseValues = new TypedArray(
            bufferViews[2],
            byteOffsetValues,
            accessorDef.sparse.count * itemSize
          );

          if (bufferView !== null) {
            // Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
            bufferAttribute = new THREE.BufferAttribute(
              bufferAttribute.array.slice(),
              bufferAttribute.itemSize,
              bufferAttribute.normalized
            );
          }

          for (let i = 0, il = sparseIndices.length; i < il; i++) {
            const index = sparseIndices[i];
            bufferAttribute.setX(index, sparseValues[i * itemSize]);
            if (itemSize >= 2)
              bufferAttribute.setY(index, sparseValues[i * itemSize + 1]);
            if (itemSize >= 3)
              bufferAttribute.setZ(index, sparseValues[i * itemSize + 2]);
            if (itemSize >= 4)
              bufferAttribute.setW(index, sparseValues[i * itemSize + 3]);
            if (itemSize >= 5)
              throw new Error(
                'THREE.GLTFLoader: Unsupported itemSize in sparse THREE.BufferAttribute.'
              );
          }
        }

        return bufferAttribute;
      });
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
     * @param {number} textureIndex
     * @return {Promise<THREE.Texture>}
     */

    loadTexture(textureIndex) {
      const json = this.json;
      const options = this.options;
      const textureDef = json.textures[textureIndex];
      const source = json.images[textureDef.source];
      let loader = this.textureLoader;

      if (source.uri) {
        const handler = options.manager.getHandler(source.uri);
        if (handler !== null) loader = handler;
      }

      return this.loadTextureImage(textureIndex, source, loader);
    }

    loadTextureImage(textureIndex, source, loader) {
      const parser = this;
      const json = this.json;
      const options = this.options;
      const textureDef = json.textures[textureIndex];
      const cacheKey =
        (source.uri || source.bufferView) + ':' + textureDef.sampler;

      if (this.textureCache[cacheKey]) {
        // See https://github.com/mrdoob/three.js/issues/21559.
        return this.textureCache[cacheKey];
      }

      const URL = self.URL || self.webkitURL;
      let sourceURI = source.uri || '';
      let isObjectURL = false;
      let hasAlpha = true;
      const isJPEG =
        sourceURI.search(/\.jpe?g($|\?)/i) > 0 ||
        sourceURI.search(/^data\:image\/jpeg/) === 0;
      if (source.mimeType === 'image/jpeg' || isJPEG) hasAlpha = false;

      if (source.bufferView !== undefined) {
        // Load binary image data from bufferView, if provided.
        sourceURI = parser
          .getDependency('bufferView', source.bufferView)
          .then(function (bufferView) {
            if (source.mimeType === 'image/png') {
              // Inspect the PNG 'IHDR' chunk to determine whether the image could have an
              // alpha channel. This check is conservative — the image could have an alpha
              // channel with all values == 1, and the indexed type (colorType == 3) only
              // sometimes contains alpha.
              //
              // https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
              const colorType = new DataView(bufferView, 25, 1).getUint8(
                0,
                false
              );
              hasAlpha = colorType === 6 || colorType === 4 || colorType === 3;
            }

            isObjectURL = true;
            const blob = new Blob([bufferView], {
              type: source.mimeType,
            });
            sourceURI = URL.createObjectURL(blob);
            return sourceURI;
          });
      } else if (source.uri === undefined) {
        throw new Error(
          'THREE.GLTFLoader: Image ' +
            textureIndex +
            ' is missing URI and bufferView'
        );
      }

      const promise = Promise.resolve(sourceURI)
        .then(function (sourceURI) {
          return new Promise(function (resolve, reject) {
            let onLoad = resolve;

            if (loader.isImageBitmapLoader === true) {
              onLoad = function (imageBitmap) {
                const texture = new THREE.Texture(imageBitmap);
                texture.needsUpdate = true;
                resolve(texture);
              };
            }

            loader.load(
              resolveURL(sourceURI, options.path),
              onLoad,
              undefined,
              reject
            );
          });
        })
        .then(function (texture) {
          // Clean up resources and configure THREE.Texture.
          if (isObjectURL === true) {
            URL.revokeObjectURL(sourceURI);
          }

          texture.flipY = false;
          if (textureDef.name) texture.name = textureDef.name; // When there is definitely no alpha channel in the texture, set THREE.RGBFormat to save space.

          if (!hasAlpha) texture.format = THREE.RGBFormat;
          const samplers = json.samplers || {};
          const sampler = samplers[textureDef.sampler] || {};
          texture.magFilter =
            WEBGL_FILTERS[sampler.magFilter] || THREE.LinearFilter;
          texture.minFilter =
            WEBGL_FILTERS[sampler.minFilter] || THREE.LinearMipmapLinearFilter;
          texture.wrapS =
            WEBGL_WRAPPINGS[sampler.wrapS] || THREE.RepeatWrapping;
          texture.wrapT =
            WEBGL_WRAPPINGS[sampler.wrapT] || THREE.RepeatWrapping;
          parser.associations.set(texture, {
            type: 'textures',
            index: textureIndex,
          });
          return texture;
        })
        .catch(function () {
          console.error("THREE.GLTFLoader: Couldn't load texture", sourceURI);
          return null;
        });
      this.textureCache[cacheKey] = promise;
      return promise;
    }
    /**
     * Asynchronously assigns a texture to the given material parameters.
     * @param {Object} materialParams
     * @param {string} mapName
     * @param {Object} mapDef
     * @return {Promise<Texture>}
     */

    assignTexture(materialParams, mapName, mapDef) {
      const parser = this;
      return this.getDependency('texture', mapDef.index).then(function (
        texture
      ) {
        // Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
        // However, we will copy UV set 0 to UV set 1 on demand for aoMap
        if (
          mapDef.texCoord !== undefined &&
          mapDef.texCoord != 0 &&
          !(mapName === 'aoMap' && mapDef.texCoord == 1)
        ) {
          console.warn(
            'THREE.GLTFLoader: Custom UV set ' +
              mapDef.texCoord +
              ' for texture ' +
              mapName +
              ' not yet supported.'
          );
        }

        if (parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]) {
          const transform =
            mapDef.extensions !== undefined
              ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]
              : undefined;

          if (transform) {
            const gltfReference = parser.associations.get(texture);
            texture = parser.extensions[
              EXTENSIONS.KHR_TEXTURE_TRANSFORM
            ].extendTexture(texture, transform);
            parser.associations.set(texture, gltfReference);
          }
        }

        materialParams[mapName] = texture;
        return texture;
      });
    }
    /**
     * Assigns final material to a THREE.Mesh, THREE.Line, or THREE.Points instance. The instance
     * already has a material (generated from the glTF material options alone)
     * but reuse of the same glTF material may require multiple threejs materials
     * to accommodate different primitive types, defines, etc. New materials will
     * be created if necessary, and reused from a cache.
     * @param  {Object3D} mesh THREE.Mesh, THREE.Line, or THREE.Points instance.
     */

    assignFinalMaterial(mesh) {
      const geometry = mesh.geometry;
      let material = mesh.material;
      const useVertexTangents = geometry.attributes.tangent !== undefined;
      const useVertexColors = geometry.attributes.color !== undefined;
      const useFlatShading = geometry.attributes.normal === undefined;

      if (mesh.isPoints) {
        const cacheKey = 'PointsMaterial:' + material.uuid;
        let pointsMaterial = this.cache.get(cacheKey);

        if (!pointsMaterial) {
          pointsMaterial = new THREE.PointsMaterial();
          THREE.Material.prototype.copy.call(pointsMaterial, material);
          pointsMaterial.color.copy(material.color);
          pointsMaterial.map = material.map;
          pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px

          this.cache.add(cacheKey, pointsMaterial);
        }

        material = pointsMaterial;
      } else if (mesh.isLine) {
        const cacheKey = 'LineBasicMaterial:' + material.uuid;
        let lineMaterial = this.cache.get(cacheKey);

        if (!lineMaterial) {
          lineMaterial = new THREE.LineBasicMaterial();
          THREE.Material.prototype.copy.call(lineMaterial, material);
          lineMaterial.color.copy(material.color);
          this.cache.add(cacheKey, lineMaterial);
        }

        material = lineMaterial;
      } // Clone the material if it will be modified

      if (useVertexTangents || useVertexColors || useFlatShading) {
        let cacheKey = 'ClonedMaterial:' + material.uuid + ':';
        if (material.isGLTFSpecularGlossinessMaterial)
          cacheKey += 'specular-glossiness:';
        if (useVertexTangents) cacheKey += 'vertex-tangents:';
        if (useVertexColors) cacheKey += 'vertex-colors:';
        if (useFlatShading) cacheKey += 'flat-shading:';
        let cachedMaterial = this.cache.get(cacheKey);

        if (!cachedMaterial) {
          cachedMaterial = material.clone();
          if (useVertexColors) cachedMaterial.vertexColors = true;
          if (useFlatShading) cachedMaterial.flatShading = true;

          if (useVertexTangents) {
            // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
            if (cachedMaterial.normalScale) cachedMaterial.normalScale.y *= -1;
            if (cachedMaterial.clearcoatNormalScale)
              cachedMaterial.clearcoatNormalScale.y *= -1;
          }

          this.cache.add(cacheKey, cachedMaterial);
          this.associations.set(
            cachedMaterial,
            this.associations.get(material)
          );
        }

        material = cachedMaterial;
      } // workarounds for mesh and geometry

      if (
        material.aoMap &&
        geometry.attributes.uv2 === undefined &&
        geometry.attributes.uv !== undefined
      ) {
        geometry.setAttribute('uv2', geometry.attributes.uv);
      }

      mesh.material = material;
    }

    getMaterialType() {
      return THREE.MeshStandardMaterial;
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
     * @param {number} materialIndex
     * @return {Promise<Material>}
     */

    loadMaterial(materialIndex) {
      const parser = this;
      const json = this.json;
      const extensions = this.extensions;
      const materialDef = json.materials[materialIndex];
      let materialType;
      const materialParams = {};
      const materialExtensions = materialDef.extensions || {};
      const pending = [];

      if (
        materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]
      ) {
        const sgExtension =
          extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS];
        materialType = sgExtension.getMaterialType();
        pending.push(
          sgExtension.extendParams(materialParams, materialDef, parser)
        );
      } else if (materialExtensions[EXTENSIONS.KHR_MATERIALS_UNLIT]) {
        const kmuExtension = extensions[EXTENSIONS.KHR_MATERIALS_UNLIT];
        materialType = kmuExtension.getMaterialType();
        pending.push(
          kmuExtension.extendParams(materialParams, materialDef, parser)
        );
      } else {
        // Specification:
        // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material
        const metallicRoughness = materialDef.pbrMetallicRoughness || {};
        materialParams.color = new THREE.Color(1.0, 1.0, 1.0);
        materialParams.opacity = 1.0;

        if (Array.isArray(metallicRoughness.baseColorFactor)) {
          const array = metallicRoughness.baseColorFactor;
          materialParams.color.fromArray(array);
          materialParams.opacity = array[3];
        }

        if (metallicRoughness.baseColorTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              'map',
              metallicRoughness.baseColorTexture
            )
          );
        }

        materialParams.metalness =
          metallicRoughness.metallicFactor !== undefined
            ? metallicRoughness.metallicFactor
            : 1.0;
        materialParams.roughness =
          metallicRoughness.roughnessFactor !== undefined
            ? metallicRoughness.roughnessFactor
            : 1.0;

        if (metallicRoughness.metallicRoughnessTexture !== undefined) {
          pending.push(
            parser.assignTexture(
              materialParams,
              'metalnessMap',
              metallicRoughness.metallicRoughnessTexture
            )
          );
          pending.push(
            parser.assignTexture(
              materialParams,
              'roughnessMap',
              metallicRoughness.metallicRoughnessTexture
            )
          );
        }

        materialType = this._invokeOne(function (ext) {
          return ext.getMaterialType && ext.getMaterialType(materialIndex);
        });
        pending.push(
          Promise.all(
            this._invokeAll(function (ext) {
              return (
                ext.extendMaterialParams &&
                ext.extendMaterialParams(materialIndex, materialParams)
              );
            })
          )
        );
      }

      if (materialDef.doubleSided === true) {
        materialParams.side = THREE.DoubleSide;
      }

      const alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

      if (alphaMode === ALPHA_MODES.BLEND) {
        materialParams.transparent = true; // See: https://github.com/mrdoob/three.js/issues/17706

        materialParams.depthWrite = false;
      } else {
        materialParams.format = THREE.RGBFormat;
        materialParams.transparent = false;

        if (alphaMode === ALPHA_MODES.MASK) {
          materialParams.alphaTest =
            materialDef.alphaCutoff !== undefined
              ? materialDef.alphaCutoff
              : 0.5;
        }
      }

      if (
        materialDef.normalTexture !== undefined &&
        materialType !== THREE.MeshBasicMaterial
      ) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'normalMap',
            materialDef.normalTexture
          )
        ); // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995

        materialParams.normalScale = new THREE.Vector2(1, -1);

        if (materialDef.normalTexture.scale !== undefined) {
          materialParams.normalScale.set(
            materialDef.normalTexture.scale,
            -materialDef.normalTexture.scale
          );
        }
      }

      if (
        materialDef.occlusionTexture !== undefined &&
        materialType !== THREE.MeshBasicMaterial
      ) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'aoMap',
            materialDef.occlusionTexture
          )
        );

        if (materialDef.occlusionTexture.strength !== undefined) {
          materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;
        }
      }

      if (
        materialDef.emissiveFactor !== undefined &&
        materialType !== THREE.MeshBasicMaterial
      ) {
        materialParams.emissive = new THREE.Color().fromArray(
          materialDef.emissiveFactor
        );
      }

      if (
        materialDef.emissiveTexture !== undefined &&
        materialType !== THREE.MeshBasicMaterial
      ) {
        pending.push(
          parser.assignTexture(
            materialParams,
            'emissiveMap',
            materialDef.emissiveTexture
          )
        );
      }

      return Promise.all(pending).then(function () {
        let material;

        if (materialType === GLTFMeshStandardSGMaterial) {
          material =
            extensions[
              EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS
            ].createMaterial(materialParams);
        } else {
          material = new materialType(materialParams);
        }

        if (materialDef.name) material.name = materialDef.name; // baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.

        if (material.map) material.map.encoding = THREE.sRGBEncoding;
        if (material.emissiveMap)
          material.emissiveMap.encoding = THREE.sRGBEncoding;
        assignExtrasToUserData(material, materialDef);
        parser.associations.set(material, {
          type: 'materials',
          index: materialIndex,
        });
        if (materialDef.extensions)
          addUnknownExtensionsToUserData(extensions, material, materialDef);
        return material;
      });
    }
    /** When THREE.Object3D instances are targeted by animation, they need unique names. */

    createUniqueName(originalName) {
      const sanitizedName = THREE.PropertyBinding.sanitizeNodeName(
        originalName || ''
      );
      let name = sanitizedName;

      for (let i = 1; this.nodeNamesUsed[name]; ++i) {
        name = sanitizedName + '_' + i;
      }

      this.nodeNamesUsed[name] = true;
      return name;
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
     *
     * Creates BufferGeometries from primitives.
     *
     * @param {Array<GLTF.Primitive>} primitives
     * @return {Promise<Array<BufferGeometry>>}
     */

    loadGeometries(primitives) {
      const parser = this;
      const extensions = this.extensions;
      const cache = this.primitiveCache;

      function createDracoPrimitive(primitive) {
        return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
          .decodePrimitive(primitive, parser)
          .then(function (geometry) {
            return addPrimitiveAttributes(geometry, primitive, parser);
          });
      }

      const pending = [];

      for (let i = 0, il = primitives.length; i < il; i++) {
        const primitive = primitives[i];
        const cacheKey = createPrimitiveKey(primitive); // See if we've already created this geometry

        const cached = cache[cacheKey];

        if (cached) {
          // Use the cached geometry if it exists
          pending.push(cached.promise);
        } else {
          let geometryPromise;

          if (
            primitive.extensions &&
            primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
          ) {
            // Use DRACO geometry if available
            geometryPromise = createDracoPrimitive(primitive);
          } else {
            // Otherwise create a new geometry
            geometryPromise = addPrimitiveAttributes(
              new THREE.BufferGeometry(),
              primitive,
              parser
            );
          } // Cache this geometry

          cache[cacheKey] = {
            primitive: primitive,
            promise: geometryPromise,
          };
          pending.push(geometryPromise);
        }
      }

      return Promise.all(pending);
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
     * @param {number} meshIndex
     * @return {Promise<Group|Mesh|SkinnedMesh>}
     */

    loadMesh(meshIndex) {
      const parser = this;
      const json = this.json;
      const extensions = this.extensions;
      const meshDef = json.meshes[meshIndex];
      const primitives = meshDef.primitives;
      const pending = [];

      for (let i = 0, il = primitives.length; i < il; i++) {
        const material =
          primitives[i].material === undefined
            ? createDefaultMaterial(this.cache)
            : this.getDependency('material', primitives[i].material);
        pending.push(material);
      }

      pending.push(parser.loadGeometries(primitives));
      return Promise.all(pending).then(function (results) {
        const materials = results.slice(0, results.length - 1);
        const geometries = results[results.length - 1];
        const meshes = [];

        for (let i = 0, il = geometries.length; i < il; i++) {
          const geometry = geometries[i];
          const primitive = primitives[i]; // 1. create THREE.Mesh

          let mesh;
          const material = materials[i];

          if (
            primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
            primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
            primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
            primitive.mode === undefined
          ) {
            // .isSkinnedMesh isn't in glTF spec. See ._markDefs()
            mesh =
              meshDef.isSkinnedMesh === true
                ? new THREE.SkinnedMesh(geometry, material)
                : new THREE.Mesh(geometry, material);

            if (
              mesh.isSkinnedMesh === true &&
              !mesh.geometry.attributes.skinWeight.normalized
            ) {
              // we normalize floating point skin weight array to fix malformed assets (see #15319)
              // it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
              mesh.normalizeSkinWeights();
            }

            if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {
              mesh.geometry = toTrianglesDrawMode(
                mesh.geometry,
                THREE.TriangleStripDrawMode
              );
            } else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {
              mesh.geometry = toTrianglesDrawMode(
                mesh.geometry,
                THREE.TriangleFanDrawMode
              );
            }
          } else if (primitive.mode === WEBGL_CONSTANTS.LINES) {
            mesh = new THREE.LineSegments(geometry, material);
          } else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {
            mesh = new THREE.Line(geometry, material);
          } else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {
            mesh = new THREE.LineLoop(geometry, material);
          } else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {
            mesh = new THREE.Points(geometry, material);
          } else {
            throw new Error(
              'THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode
            );
          }

          if (Object.keys(mesh.geometry.morphAttributes).length > 0) {
            updateMorphTargets(mesh, meshDef);
          }

          mesh.name = parser.createUniqueName(
            meshDef.name || 'mesh_' + meshIndex
          );
          assignExtrasToUserData(mesh, meshDef);
          if (primitive.extensions)
            addUnknownExtensionsToUserData(extensions, mesh, primitive);
          parser.assignFinalMaterial(mesh);
          meshes.push(mesh);
        }

        if (meshes.length === 1) {
          return meshes[0];
        }

        const group = new THREE.Group();

        for (let i = 0, il = meshes.length; i < il; i++) {
          group.add(meshes[i]);
        }

        return group;
      });
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
     * @param {number} cameraIndex
     * @return {Promise<THREE.Camera>}
     */

    loadCamera(cameraIndex) {
      let camera;
      const cameraDef = this.json.cameras[cameraIndex];
      const params = cameraDef[cameraDef.type];

      if (!params) {
        console.warn('THREE.GLTFLoader: Missing camera parameters.');
        return;
      }

      if (cameraDef.type === 'perspective') {
        camera = new THREE.PerspectiveCamera(
          THREE.MathUtils.radToDeg(params.yfov),
          params.aspectRatio || 1,
          params.znear || 1,
          params.zfar || 2e6
        );
      } else if (cameraDef.type === 'orthographic') {
        camera = new THREE.OrthographicCamera(
          -params.xmag,
          params.xmag,
          params.ymag,
          -params.ymag,
          params.znear,
          params.zfar
        );
      }

      if (cameraDef.name) camera.name = this.createUniqueName(cameraDef.name);
      assignExtrasToUserData(camera, cameraDef);
      return Promise.resolve(camera);
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
     * @param {number} skinIndex
     * @return {Promise<Object>}
     */

    loadSkin(skinIndex) {
      const skinDef = this.json.skins[skinIndex];
      const skinEntry = {
        joints: skinDef.joints,
      };

      if (skinDef.inverseBindMatrices === undefined) {
        return Promise.resolve(skinEntry);
      }

      return this.getDependency('accessor', skinDef.inverseBindMatrices).then(
        function (accessor) {
          skinEntry.inverseBindMatrices = accessor;
          return skinEntry;
        }
      );
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
     * @param {number} animationIndex
     * @return {Promise<AnimationClip>}
     */

    loadAnimation(animationIndex) {
      const json = this.json;
      const animationDef = json.animations[animationIndex];
      const pendingNodes = [];
      const pendingInputAccessors = [];
      const pendingOutputAccessors = [];
      const pendingSamplers = [];
      const pendingTargets = [];

      for (let i = 0, il = animationDef.channels.length; i < il; i++) {
        const channel = animationDef.channels[i];
        const sampler = animationDef.samplers[channel.sampler];
        const target = channel.target;
        const name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.

        const input =
          animationDef.parameters !== undefined
            ? animationDef.parameters[sampler.input]
            : sampler.input;
        const output =
          animationDef.parameters !== undefined
            ? animationDef.parameters[sampler.output]
            : sampler.output;
        pendingNodes.push(this.getDependency('node', name));
        pendingInputAccessors.push(this.getDependency('accessor', input));
        pendingOutputAccessors.push(this.getDependency('accessor', output));
        pendingSamplers.push(sampler);
        pendingTargets.push(target);
      }

      return Promise.all([
        Promise.all(pendingNodes),
        Promise.all(pendingInputAccessors),
        Promise.all(pendingOutputAccessors),
        Promise.all(pendingSamplers),
        Promise.all(pendingTargets),
      ]).then(function (dependencies) {
        const nodes = dependencies[0];
        const inputAccessors = dependencies[1];
        const outputAccessors = dependencies[2];
        const samplers = dependencies[3];
        const targets = dependencies[4];
        const tracks = [];

        for (let i = 0, il = nodes.length; i < il; i++) {
          const node = nodes[i];
          const inputAccessor = inputAccessors[i];
          const outputAccessor = outputAccessors[i];
          const sampler = samplers[i];
          const target = targets[i];
          if (node === undefined) continue;
          node.updateMatrix();
          node.matrixAutoUpdate = true;
          let TypedKeyframeTrack;

          switch (PATH_PROPERTIES[target.path]) {
            case PATH_PROPERTIES.weights:
              TypedKeyframeTrack = THREE.NumberKeyframeTrack;
              break;

            case PATH_PROPERTIES.rotation:
              TypedKeyframeTrack = THREE.QuaternionKeyframeTrack;
              break;

            case PATH_PROPERTIES.position:
            case PATH_PROPERTIES.scale:
            default:
              TypedKeyframeTrack = THREE.VectorKeyframeTrack;
              break;
          }

          const targetName = node.name ? node.name : node.uuid;
          const interpolation =
            sampler.interpolation !== undefined
              ? INTERPOLATION[sampler.interpolation]
              : THREE.InterpolateLinear;
          const targetNames = [];

          if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {
            // Node may be a THREE.Group (glTF mesh with several primitives) or a THREE.Mesh.
            node.traverse(function (object) {
              if (object.isMesh === true && object.morphTargetInfluences) {
                targetNames.push(object.name ? object.name : object.uuid);
              }
            });
          } else {
            targetNames.push(targetName);
          }

          let outputArray = outputAccessor.array;

          if (outputAccessor.normalized) {
            const scale = getNormalizedComponentScale(outputArray.constructor);
            const scaled = new Float32Array(outputArray.length);

            for (let j = 0, jl = outputArray.length; j < jl; j++) {
              scaled[j] = outputArray[j] * scale;
            }

            outputArray = scaled;
          }

          for (let j = 0, jl = targetNames.length; j < jl; j++) {
            const track = new TypedKeyframeTrack(
              targetNames[j] + '.' + PATH_PROPERTIES[target.path],
              inputAccessor.array,
              outputArray,
              interpolation
            ); // Override interpolation with custom factory method.

            if (sampler.interpolation === 'CUBICSPLINE') {
              track.createInterpolant =
                function InterpolantFactoryMethodGLTFCubicSpline(result) {
                  // A CUBICSPLINE keyframe in glTF has three output values for each input value,
                  // representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
                  // must be divided by three to get the interpolant's sampleSize argument.
                  const interpolantType =
                    this instanceof THREE.QuaternionKeyframeTrack
                      ? GLTFCubicSplineQuaternionInterpolant
                      : GLTFCubicSplineInterpolant;
                  return new interpolantType(
                    this.times,
                    this.values,
                    this.getValueSize() / 3,
                    result
                  );
                }; // Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.

              track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;
            }

            tracks.push(track);
          }
        }

        const name = animationDef.name
          ? animationDef.name
          : 'animation_' + animationIndex;
        return new THREE.AnimationClip(name, undefined, tracks);
      });
    }

    createNodeMesh(nodeIndex) {
      const json = this.json;
      const parser = this;
      const nodeDef = json.nodes[nodeIndex];
      if (nodeDef.mesh === undefined) return null;
      return parser.getDependency('mesh', nodeDef.mesh).then(function (mesh) {
        const node = parser._getNodeRef(parser.meshCache, nodeDef.mesh, mesh); // if weights are provided on the node, override weights on the mesh.

        if (nodeDef.weights !== undefined) {
          node.traverse(function (o) {
            if (!o.isMesh) return;

            for (let i = 0, il = nodeDef.weights.length; i < il; i++) {
              o.morphTargetInfluences[i] = nodeDef.weights[i];
            }
          });
        }

        return node;
      });
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
     * @param {number} nodeIndex
     * @return {Promise<Object3D>}
     */

    loadNode(nodeIndex) {
      const json = this.json;
      const extensions = this.extensions;
      const parser = this;
      const nodeDef = json.nodes[nodeIndex]; // reserve node's name before its dependencies, so the root has the intended name.

      const nodeName = nodeDef.name
        ? parser.createUniqueName(nodeDef.name)
        : '';
      return (function () {
        const pending = [];

        const meshPromise = parser._invokeOne(function (ext) {
          return ext.createNodeMesh && ext.createNodeMesh(nodeIndex);
        });

        if (meshPromise) {
          pending.push(meshPromise);
        }

        if (nodeDef.camera !== undefined) {
          pending.push(
            parser
              .getDependency('camera', nodeDef.camera)
              .then(function (camera) {
                return parser._getNodeRef(
                  parser.cameraCache,
                  nodeDef.camera,
                  camera
                );
              })
          );
        }

        parser
          ._invokeAll(function (ext) {
            return (
              ext.createNodeAttachment && ext.createNodeAttachment(nodeIndex)
            );
          })
          .forEach(function (promise) {
            pending.push(promise);
          });

        return Promise.all(pending);
      })().then(function (objects) {
        let node; // .isBone isn't in glTF spec. See ._markDefs

        if (nodeDef.isBone === true) {
          node = new THREE.Bone();
        } else if (objects.length > 1) {
          node = new THREE.Group();
        } else if (objects.length === 1) {
          node = objects[0];
        } else {
          node = new THREE.Object3D();
        }

        if (node !== objects[0]) {
          for (let i = 0, il = objects.length; i < il; i++) {
            node.add(objects[i]);
          }
        }

        if (nodeDef.name) {
          node.userData.name = nodeDef.name;
          node.name = nodeName;
        }

        assignExtrasToUserData(node, nodeDef);
        if (nodeDef.extensions)
          addUnknownExtensionsToUserData(extensions, node, nodeDef);

        if (nodeDef.matrix !== undefined) {
          const matrix = new THREE.Matrix4();
          matrix.fromArray(nodeDef.matrix);
          node.applyMatrix4(matrix);
        } else {
          if (nodeDef.translation !== undefined) {
            node.position.fromArray(nodeDef.translation);
          }

          if (nodeDef.rotation !== undefined) {
            node.quaternion.fromArray(nodeDef.rotation);
          }

          if (nodeDef.scale !== undefined) {
            node.scale.fromArray(nodeDef.scale);
          }
        }

        parser.associations.set(node, {
          type: 'nodes',
          index: nodeIndex,
        });
        return node;
      });
    }
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
     * @param {number} sceneIndex
     * @return {Promise<Group>}
     */

    loadScene(sceneIndex) {
      const json = this.json;
      const extensions = this.extensions;
      const sceneDef = this.json.scenes[sceneIndex];
      const parser = this; // THREE.Loader returns THREE.Group, not Scene.
      // See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172

      const scene = new THREE.Group();
      if (sceneDef.name) scene.name = parser.createUniqueName(sceneDef.name);
      assignExtrasToUserData(scene, sceneDef);
      if (sceneDef.extensions)
        addUnknownExtensionsToUserData(extensions, scene, sceneDef);
      const nodeIds = sceneDef.nodes || [];
      const pending = [];

      for (let i = 0, il = nodeIds.length; i < il; i++) {
        pending.push(buildNodeHierachy(nodeIds[i], scene, json, parser));
      }

      return Promise.all(pending).then(function () {
        return scene;
      });
    }
  }

  function buildNodeHierachy(nodeId, parentObject, json, parser) {
    const nodeDef = json.nodes[nodeId];
    return parser
      .getDependency('node', nodeId)
      .then(function (node) {
        if (nodeDef.skin === undefined) return node; // build skeleton here as well

        let skinEntry;
        return parser
          .getDependency('skin', nodeDef.skin)
          .then(function (skin) {
            skinEntry = skin;
            const pendingJoints = [];

            for (let i = 0, il = skinEntry.joints.length; i < il; i++) {
              pendingJoints.push(
                parser.getDependency('node', skinEntry.joints[i])
              );
            }

            return Promise.all(pendingJoints);
          })
          .then(function (jointNodes) {
            node.traverse(function (mesh) {
              if (!mesh.isMesh) return;
              const bones = [];
              const boneInverses = [];

              for (let j = 0, jl = jointNodes.length; j < jl; j++) {
                const jointNode = jointNodes[j];

                if (jointNode) {
                  bones.push(jointNode);
                  const mat = new THREE.Matrix4();

                  if (skinEntry.inverseBindMatrices !== undefined) {
                    mat.fromArray(skinEntry.inverseBindMatrices.array, j * 16);
                  }

                  boneInverses.push(mat);
                } else {
                  console.warn(
                    'THREE.GLTFLoader: Joint "%s" could not be found.',
                    skinEntry.joints[j]
                  );
                }
              }

              mesh.bind(
                new THREE.Skeleton(bones, boneInverses),
                mesh.matrixWorld
              );
            });
            return node;
          });
      })
      .then(function (node) {
        // build node hierachy
        parentObject.add(node);
        const pending = [];

        if (nodeDef.children) {
          const children = nodeDef.children;

          for (let i = 0, il = children.length; i < il; i++) {
            const child = children[i];
            pending.push(buildNodeHierachy(child, node, json, parser));
          }
        }

        return Promise.all(pending);
      });
  }
  /**
   * @param {BufferGeometry} geometry
   * @param {GLTF.Primitive} primitiveDef
   * @param {GLTFParser} parser
   */

  function computeBounds(geometry, primitiveDef, parser) {
    const attributes = primitiveDef.attributes;
    const box = new THREE.Box3();

    if (attributes.POSITION !== undefined) {
      const accessor = parser.json.accessors[attributes.POSITION];
      const min = accessor.min;
      const max = accessor.max; // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

      if (min !== undefined && max !== undefined) {
        box.set(
          new THREE.Vector3(min[0], min[1], min[2]),
          new THREE.Vector3(max[0], max[1], max[2])
        );

        if (accessor.normalized) {
          const boxScale = getNormalizedComponentScale(
            WEBGL_COMPONENT_TYPES[accessor.componentType]
          );
          box.min.multiplyScalar(boxScale);
          box.max.multiplyScalar(boxScale);
        }
      } else {
        console.warn(
          'THREE.GLTFLoader: Missing min/max properties for accessor POSITION.'
        );
        return;
      }
    } else {
      return;
    }

    const targets = primitiveDef.targets;

    if (targets !== undefined) {
      const maxDisplacement = new THREE.Vector3();
      const vector = new THREE.Vector3();

      for (let i = 0, il = targets.length; i < il; i++) {
        const target = targets[i];

        if (target.POSITION !== undefined) {
          const accessor = parser.json.accessors[target.POSITION];
          const min = accessor.min;
          const max = accessor.max; // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

          if (min !== undefined && max !== undefined) {
            // we need to get max of absolute components because target weight is [-1,1]
            vector.setX(Math.max(Math.abs(min[0]), Math.abs(max[0])));
            vector.setY(Math.max(Math.abs(min[1]), Math.abs(max[1])));
            vector.setZ(Math.max(Math.abs(min[2]), Math.abs(max[2])));

            if (accessor.normalized) {
              const boxScale = getNormalizedComponentScale(
                WEBGL_COMPONENT_TYPES[accessor.componentType]
              );
              vector.multiplyScalar(boxScale);
            } // Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
            // to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
            // are used to implement key-frame animations and as such only two are active at a time - this results in very large
            // boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.

            maxDisplacement.max(vector);
          } else {
            console.warn(
              'THREE.GLTFLoader: Missing min/max properties for accessor POSITION.'
            );
          }
        }
      } // As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.

      box.expandByVector(maxDisplacement);
    }

    geometry.boundingBox = box;
    const sphere = new THREE.Sphere();
    box.getCenter(sphere.center);
    sphere.radius = box.min.distanceTo(box.max) / 2;
    geometry.boundingSphere = sphere;
  }
  /**
   * @param {BufferGeometry} geometry
   * @param {GLTF.Primitive} primitiveDef
   * @param {GLTFParser} parser
   * @return {Promise<BufferGeometry>}
   */

  function addPrimitiveAttributes(geometry, primitiveDef, parser) {
    const attributes = primitiveDef.attributes;
    const pending = [];

    function assignAttributeAccessor(accessorIndex, attributeName) {
      return parser
        .getDependency('accessor', accessorIndex)
        .then(function (accessor) {
          geometry.setAttribute(attributeName, accessor);
        });
    }

    for (const gltfAttributeName in attributes) {
      const threeAttributeName =
        ATTRIBUTES[gltfAttributeName] || gltfAttributeName.toLowerCase(); // Skip attributes already provided by e.g. Draco extension.

      if (threeAttributeName in geometry.attributes) continue;
      pending.push(
        assignAttributeAccessor(
          attributes[gltfAttributeName],
          threeAttributeName
        )
      );
    }

    if (primitiveDef.indices !== undefined && !geometry.index) {
      const accessor = parser
        .getDependency('accessor', primitiveDef.indices)
        .then(function (accessor) {
          geometry.setIndex(accessor);
        });
      pending.push(accessor);
    }

    assignExtrasToUserData(geometry, primitiveDef);
    computeBounds(geometry, primitiveDef, parser);
    return Promise.all(pending).then(function () {
      return primitiveDef.targets !== undefined
        ? addMorphTargets(geometry, primitiveDef.targets, parser)
        : geometry;
    });
  }
  /**
   * @param {BufferGeometry} geometry
   * @param {Number} drawMode
   * @return {BufferGeometry}
   */

  function toTrianglesDrawMode(geometry, drawMode) {
    let index = geometry.getIndex(); // generate index if not present

    if (index === null) {
      const indices = [];
      const position = geometry.getAttribute('position');

      if (position !== undefined) {
        for (let i = 0; i < position.count; i++) {
          indices.push(i);
        }

        geometry.setIndex(indices);
        index = geometry.getIndex();
      } else {
        console.error(
          'THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.'
        );
        return geometry;
      }
    } //

    const numberOfTriangles = index.count - 2;
    const newIndices = [];

    if (drawMode === THREE.TriangleFanDrawMode) {
      // gl.TRIANGLE_FAN
      for (let i = 1; i <= numberOfTriangles; i++) {
        newIndices.push(index.getX(0));
        newIndices.push(index.getX(i));
        newIndices.push(index.getX(i + 1));
      }
    } else {
      // gl.TRIANGLE_STRIP
      for (let i = 0; i < numberOfTriangles; i++) {
        if (i % 2 === 0) {
          newIndices.push(index.getX(i));
          newIndices.push(index.getX(i + 1));
          newIndices.push(index.getX(i + 2));
        } else {
          newIndices.push(index.getX(i + 2));
          newIndices.push(index.getX(i + 1));
          newIndices.push(index.getX(i));
        }
      }
    }

    if (newIndices.length / 3 !== numberOfTriangles) {
      console.error(
        'THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.'
      );
    } // build final geometry

    const newGeometry = geometry.clone();
    newGeometry.setIndex(newIndices);
    return newGeometry;
  }

  THREE.GLTFLoader = GLTFLoader;
})();
